Atomic scale Moiré patterns to push electronic boundaries?

An atomic scale version of the phenomenon that forms interference patterns on television displays may help electronics design to push the current limits of size and speed.

Moiré patterns occur on displays when the pixelation is at almost the same scale as a photographed pattern or when two thin layers of a material with a periodic structure – like sheer fabrics – are placed on top of each other slightly askew. At the macro scale, Moirés are optical phenomena that do not form tangible objects. However, researchers at the University of Illinois say that when these patterns occur at the atomic level, arrangements of electrons are locked into place by atomic forces to form nanoscale wires capable of transmitting electricity.

For decades, the team said, physicists have observed microscope images of atomic arrangements of 2D thin films and recognised them as dislocations. But Professor Harley Johnson’s group is the first to note that these are also common Moiré patterns.

Prof Johnson said: “2D materials – thin films engineered to be of single-atom thickness – create Moiré patterns when stacked on top of each other and are skewed, stretched, compressed or twisted. The Moiré emerges as atoms form linear areas of high electron density. The resulting lines create what is essentially an extremely thin wire.”

By manipulating the orientation of stacked layers of 2D thin films, such as graphene, wires of single-atom thickness can be assembled, building the foundation to write nanocircuitry. This has the potential to produce the quickest transmitting wires and circuits possible, the researchers said.

“There is always the question of how to connect to a circuit that small,” Prof Johnson continued. “There is still a lot of work to be done in finding ways to stitch together 2D materials in a way that could produce a device.”

In the meantime, Prof Johnson’s group is focusing on types of devices that can be made using moire engineering. “Being able to engineer the Moiré pattern itself is a path to new lightweight and less-intrusive devices that could have applications in the biomedical and space industries,” he concluded. “The possibilities are limited only by the imagination of engineers.”